In U.S. Pat. No. 3,804,557 to Bentley, issued Apr. 16, 1974, there is disclosed a single tube surface operated pump which includes as essential elements an underground pump located at the level of the liquid being pumped, and a single tube extending from the underground pump to a pulse generator at the ground surface. The underground pump is operated by pulsations on the column of liquid being pumped which are created by the pulse generator. The latter comprises a cylinder in which a piston is reciprocated from an appropriate power source. The cylinder is formed with a lateral port which communicates with a receiving tank. On a down-stroke of the piston, this port is closed and a pulse is imparted to the column of liquid. Such pulses are transmitted through the column of liquid to the underground pump to operate it.
On the up-stroke of the piston, the lateral port is open and liquid flows into the receiving tank.
It has been found that pockets of air and gas are almost invariably present in the column of liquid. These gas pockets impair the transmission of pulses to the underground pump and, in many instances, are of such a degree as to literally render the pulses ineffective on the underground pump. Thus, by way of example, it is noted that if the pulse generator is operated to create 400 pulses per minute on the column of liquid immediately adjacent to the pulsator, the presence of air and gas in the column of liquid will often reduce the pulses which are effective on the underground pump to only a fraction of those which are generated by the pulse generator. Thus, with the latter generating 400 pulses per minute, only 100 pulses would be effective on the underground pump.
The present invention is founded on the basic concept of increasing or multiplying the pulses which are effective on the underground pump by eliminating pockets of gas and air in the column of liquid.